166 NATUBjiL HISTORY OF PLANTS. 



3. Til all the genera in which we can obtain any distinction of the 

 periaiitli into calyx and corolla, the edges of the pieces of these floral 

 envelopes overlap one another in the bud, and the calyx is imbricated. — 

 In Dr'uvys alone does it constitute a sac more or less raised, and 

 valvate in a?stivation ; this has hitherto sufficed to characterize this 

 genus among the IHicea, of which it might form a well marked sub- 

 section. 



4. The corolla, when distinct, is always polypetalous. — There is 

 only one genus of the CaneUea, Cinnamosma, in which it is distinctly 

 gamopetalous. 



5. When the ovules are solitary, or very few in number in each 

 carpel, of a descending direction, they have their micropyles turned 

 upwards and outwards, which would indicate that if ascending, the 

 micropyles would look downwards and inwards. — In Illlcium alone 

 the solitary ovules are ascending, and the micropyle looks down- 

 wards and outwards ; this is suffi.cient to characterize a special subsec- 

 tion Euilliciea among the Illiciea. 



6. In one genus alone the carpels, each containing a single placenta 

 in the internal angle, are united into a plurilocular ovary. — Every- 

 where else, where the placentas are so arranged, the carpels are free. 

 Thus we recognise Zygogynum, which might strictly be considered as 

 a special syncarpous subsection of Wmterece, or Illiciece. 



7. In Canellece alone, on the other hand, the carpels, united edge to 

 edge, form a single unilocular ovary, with several parietal placentas. — 

 These plants are then to this order what Monodora is to the 

 Anonacece, Berheridojms to Bcrberidacece, Lardizabalacece, &c. (see 

 p. 119). 



8. Only in the two genera forming the true Maynoliacea do we 

 find stipuliform expansions at the base of the leaves ; and of these all 

 the species do not possess this character ; but it is wanting in all 

 the other members of the order. 



Al\ the other characters vary in passing from one genus to another, 

 or in a single genus in passing from one species to another. These 

 are as follows : the consistency of the fruit, its dehiscence (if it opens 

 when ripe), the number of perianth leaves and of sexual organs, the 

 number of ovules in each cell, the aspect of the anthers, the existence 

 of dots on the leaves, &c. The subdivisions of minor importance 

 alone, then, may be founded on these characters. 



We have shown how, assisted by these differences in structure, 



